198 



THE SECOND BOOK OF BOTANY. 



from the cell-wall, forming a mass in the interior, as 

 shown at a (Fig. 359). Or you may get the same re- 

 sult without discoloring the cell-contents, by placing 

 the green tissue or pulp of fruits, or leaves of mosses, 

 in dilute nitric or muriatic acid. 



Take, with care, a bit of the skin from a vigorous, 

 hairy leaf, as the nettle. Put it upon the glass slide 

 with a drop of water, and examine the appearance of 

 the hairs under the microscope. Each hair, you see, 

 is a leaf-cell grown out into the air. Now drop upon 



FIG. 359. 



it spirit of wine, or something that will kill the cell, 

 and, after a time, the cell-contents will separate from 

 the cell-wall, as shown in Fig. 359. 



As to the cell-wall, it is at first a moist, soft, thin, 

 uniform membrane, which allows the free passage of 

 water through its substance; but usually a second 

 membrane appears, lining it on the inside, though it 

 does not form a complete and continuous lining. It 

 is broken in many places, making the cell- wall thick 



